it’s what i had in mind when fielding this query (a key part of desired functionality) - more of a complicated affair than 2 knobs, but essentially selectable/switchable pots (with switches) to get some ‘preset’ voltages all powered by TRS - as with all projects it takes a backseat to thinking about it though the concept is clear and simple for a novice like me - it’s just about getting the minimum order together typically … always tomorrow !